Under moderate to heavy acceleration, my car will lose power. If accelerating anywhere over 2500 rpm, after accelerating the engine rpm suddenly drops by 500-1500 rpm. Then it continues to accelerate from the lower rpm. It happens only once each time I press on the gas pedal. There are not any codes that appear. The dealership has examined the problem and they have not been able to find the cause. They ran fuel pressure tests, vacuum leakage tests, and might have checked the throttle position sensor. Can you tell me what is causing this and how to solve the problem?

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Thanks for writing in about your 2013 BMW 650i. The symptoms sound similar to a vehicle with a throttle position input error or a major boost leak in a forced induction vehicle. To verify this, I would recommend having a professional, such as one from YourMechanic, diagnose the loss of power problem in order to have this repaired properly.

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